Sound-recording apparatus.



T. A. EDISON.

SOUND RECORDING APPARATUS.

APPLICATION FILED JUNE 9, 1910.

L126$$ Patented Jan. 26, 1915.

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raarnnn oianrcn THOMAS A. EDISON, 0F LLEWELLYN EARK, WEST ORANGE, NEWERSEY, ASSIGNOR TO NEW JERSEY PATENT COMPANY, OF WEST ORANGE, NEWJERSEY, A CORPORATION OF NEW JERSEY..

SOUND-RECORDING APPTUS.

Application filed June 9, 1910. Serial No. 566,069.

To all whom it may concern: I

Be it known that I, THOMAS A. EDISON, a citizen of the United'states,and a resident of Llewellyn Park, Vest Orange, Essex county, New Jersey,have invented certain new and useful Improvements in Sound- RecordingApparatus, of which the following is a description.

My invention relates to devices for recording sound, and is animprovement on the structure described in my application Serial No.556,469, filed April 20, 1910, which application has resulted in UnitedStates Patent No. 1,019,441, dated March 5, 1912. In the applicationreferred to was described and claimed a recorder having a diaphragmcomprising a flexible ring having the upper surface of its outer edgeresting in contact with a knife edge carried by the sound box, and arigid arched circular central member, the outer edge of whichconstituted a knife edge and pressed against the lower side of the inneredge of the flexible ring. The stylus was rigidly connected" with thecenter of the rigid inner diaphragm member, and a strong upward stressgiven to the whole diaphragm, by means of a spring member upon which thestylus was carried, to hold the members of the diaphragm in position andalso to prevent excessive movement of the diaphragm away from therecording surface. This resulted in a construction of sufficientsensitiveness to respond to sound waves of little power, and one whichalso was so formed as to largely prevent excessive movements-of thediaphragm away from the recording ;sur-- face under the influence ofsound waves of great amplitude.

The object of my present invention is to improve upon the constructionjust described.

I now propose to form the flexible ring member of the diaphragm ofacetyl cellulose, or nitro-cellulose, or cellulose xanthate, (viscosecellulose), paper and like material whose porous structure permits oflarge flexing with very little power, a property absent in metals, glassand similar nonporous materials. I also now form the rin member with awide central ring-shaped corrugation, the knife-edges of the sound boxand the rigid central diaphragm member respectively contacting narrowfiat portions of the ring member on each side of Specification ofLetters Patent.

kling in the ring member is lessened, as is Patented Jan. 26, 1915.

the corrugation. By this means the action of the diaphragm is changed,so that, while the dlaphragm is just as sensitive to weak sound waves ofsmall amplitude, it is not moved away from the recording surface so farunder the influence of sound waves of great amplitude. It is worthy ofnote that when such a corrugation is formed on a ring member made ofmetal of other substance having different properties from those of thematerials mentioned, the vibrations of the same are deadened, so that nosuccessful record can be made. Also by this construction, thepossibility of huealso the tendency of the flexible member to vlbrate inparts. Another improvement, which is described and claimed herein, overthe construction shown in my previous apphcation, consists in making ajointed connection between the diaphragm and the spring lever carryingthe stylus instead of connecting the parts rigidly. As the stylus movesup and down in recording, it also moves in an are about the point atwhich the spring lever carrying the stylus is supported. If the stylusand spring lever are rigidly connected to the center of the diaphragm,the movement of the stylus in an arc tends to force the diaphragm to oneside, or to cause the same to buckle. I overcome this difliculty, asstated, by making a jointed connection between thespring lever and thediaphragm, so that the latter may freely move instraight lines towardand away from the recording surface without being acted upon by anyforces through the connection from the stylus tending to move it in anyother direction.

In order that a clear understanding of 95 my invention may be had,attention is hereby directed'to the accompanying drawings, forming partof this specification, and in which- Figure 1 represents a verticalcentral 106 cross section through a sound recorder em.- bodying one formof my invention; Fig. 2 is a bottom plan view thereof; and Fig. 3 is anenlarged detail view partly in section, showing my improved connectionbetween 105 the diaphragm and stylus.

Referring to the drawings, the sound box 1 may be provided with a recess2 to receive and guide the diaphragm. The latter con sists of a flexlbleouter portion 3 which is 110 preferably annular or ring-shaped, and aninner non-flexible portion 4. The flexible annulus 3 is preferablyformed of a cellulose composition, such as paper, acetyl cellulose,nitro-cellulose, decomposed Viscose cellulose, or other porous easilyflexing material. The annulus 3 is likewise preferably provided with awide stiffening corrugation "5 which may be either downwardly directedas shown or upwardly directed, and which occupies nearly the entirewidth of the ring, leaving very narrow flat portions 6 and 7 upon eachside of the same. The flat portions as shown, are substantially narrowerthan the corrugation. The ring 3 is Placed within recess 2 of sound box1 without touching the sides of the same and is supported by knife edge8 extending downwardly from sound box 1 within recess 2, said knife edgebeing positioned to engage the upper surface of the outer fiat portion 6of ring 3. The stilfening corrugation 5 extends outwardly nearly toknife edge 8 leaving'a very narrow portion of the ring between thecorrugation and the knife edge. The ring 3 is not secured to the soundbox by wax, rubber, or in any other way. The rigid or non-flexibleportion 4 of the diaphragm is given the form of an arch as shown, or isotherwise formed so that it will not be flexed by the vibrations of thesound waves upon it. This rigid member 4 is preferably circular in formwith its edge bent sharply upward, as shown at 9, thus forming a knifeedge contacting the lower side of the inner flat portion 7 of ring 3,quite near the inner edge of corrugation 5. The recording stylus 10 iscarried by spring lever 11, the other end of which is flattened andsecured within the sound box by screw 12.

In assembling the recorder, the ring member 3 of the diaphragm is placedimposition upon knife edge 8 with the upper surface of flat portion 6 ofthe ring adjacent the outer edge of corrugation 5 contacting the same,and the non-flexing member 4 of the diaphragm is then placed in positionwith its sharp peripheral edge 9 contacting the un der side of flatportion 7 of ring 3 near its inner edge, and also near the inner edge ofcorrugation 5. A small pin 13 having pointed or rounded ends is thenplaced in position between the end of spring member 11 and the center ofthe rigid diaphragm member 4, which are provided with conical or roundedholes or sockets 14 and 15 in which the ends of pin 13 rest, the springmember 11 being given a strong inward flex ure, so that pin 13 and thediaphragm members are held in position, and a strong upward stress givento the whole diaphragm.

The construction described provides a pin and socket or universalconnection between the stylus and diaphragm, so that as the stylus movesin an are about screw 12, the pin 13 will turn slightly in its sockets 11 and 15, without binding or buckling the diaphragm or otherwiseaffecting its straight line movement toward recording surface.

Instead of the universal connection described, I might pivot the pin 13to the diaphragm and the spring lever 11 in such a manner as to permitrelative movement of."

the pin only in a plane parallel to the axis of the spring lever 11, butthe construction shown is simpler and better.

The amount of flexure of spring member 11 may be adjusted in anysuitable manner. As shown in the drawings, I prefer to secure springmember 11 as by screw 12 to an arm 16 of block 17 secured to thesoundbox. Block 17 is formed of brass or other comparatively elasticmaterial, and arm 16 may be moved somewhat toward or away from block 17'by adjusting screw" 18, threaded through arm 16 and block 17, andthereby increasing or decreasing the initial flexure of spring member 11carried by arm 16. Le ver 19 carrying tracking member 20 may be used ifdesired, the lever and the tracking member 20 carried thereby beingadjustable to regulate the depth of cut permissible for recording stylus10. Lever 19 may be of comparatively elastic material, such as brass,cut away as shown at 21 to produce a flexible joint or hinge, the screw22 bearing on the end of the lever to regulate the position of trackingmember or ball 20.

Of the substances of which I have stated the ring member 3 may beformed, I prefer to use acetyl cellulose, since this material seems tohold its shape better than any other. Diaphragms well adapted to thedesired purpose may, however, be formed of any of the substances named,while I have found that glass, mica, and metals are not adapted for thispurpose.

Having now described my invention, what and away from the I claim anddesire to protect by Letters Patdiaphragm comprising a stifl'ened ringmember having a flexible outer edge freely mounted on said support withthe latter contacting the flexible outer edge thereof and a non-flexiblemember bridging the opening of said ring and making contact therewith,a-

recording stylus and a spring arm carrying the'stylus and by its tensionimposing an initial flexure on the diaphragm, substantially asdescribed.

3. In a sound recording apparatus, the combination with a sound box, ofa stifiened ring diaphragm having a flexible portion mounted in contactwith said sound box, a non-flexible member mounted to contact said ringdiaphragm, but not attached thereto, and a recording stylus connected tosaid non-flexible member, substantially as described.

4. In sound recording apparatus, the combination with a supporting knifeedge, of a diaphragm comprising a ring of flexible material-having outerand inner fiat portions adjacent its outer and inner edges respectively,and a corrugated portion intermediate said flat port-ions, said outerfiat portion bearing on said knife edge, a non-flexible membermounted-with its outer edge contacting said inner fiat portion but notattached thereto, and a stylus connected to said non-flexible member,substantially as described. p

5. In sound recording apparatus, the combination with a recordingstylus, of adiaphragm connected thereto comprising a rigid inner portionand an outer portion mounted to vibrate therewith, and formed of acetylcellulose, substantially as described.

6. In apparatus of the class described, the combination with a stylus,of a diaphragm connected thereto comprising a rigid inner portion and anouter ring portion mounted to vibrate therewith, but not attachedthereto, said outer ring portion being formed of a flexible porousorganic material with a central ring-shaped corrugation therein, andmeans for supporting said diaphragm contacting said ring portion outsideof said corrugation, substantially as described.

7. In apparatus of the class described, the combination with a stylus,of a diaphragm connected thereto and comprising a rigid inner portionand an outer portion formed of flexible material and having centralstiffening means, a knife edge contacting the upper surface of the outerportion on one side of said stifl'ening means, said rigid inner portionhaving a sharp outer edge contacting the under surface of said outerportion on the side of said stiffening means opposite that contacted bysaid knife edge, and elastic means for holding said inner portion incontact with said outer portion, substantially as described.

8. In sound recording apparatus, the combination with a sound box, of astiifened diaphragm member mounted therein but not secured thereto andhaving flexible free edges, a non-flexible diaphragm member mounted toVibrate with said stiffened diaphragm member but not secured thereto,

and a stylus connected to said non-flexible d aphragm member,substantially as described.

9. In sound recording apparatus, the combination with a recording stylusand a yielding member carrying the same, of a diaphragm and a connectionbetween said member and diaphragm haying universal movement with respectto said member and diaphragm, said yielding member normally exerting apressure on said connection to force the same toward said diaphragm,substantially as described.

10. In sound recording apparatus, the

combination with a sound box, of a flexible ring diaphragm mountedtherein, said diaphragm having an annular corrugation therein and beingformed of a compound of cellulose, a non-flexible member mounted tocontact one edge of said ring but not secured thereto,'an'd a recordingstylus connected to said non-flexible member, substantially asdescribed. 11. In sound recording apparatus, the combination with asound box, of a stiff corrugated annular diaphragm member mountedtherein but not secured thereto and having a free flexible inner edge, asupport engaging said member adjacent its inner edge but not securedthereto, and a stylus connected to said support and adapted to vibratewith said diaphragm member, substantially as described.

12. As a new article of manufacture, an annular diaphragm of acetylcellulose, substantially as described.

13. As a new article of manufacture, an annulanflexible diaphragm ofacetyl cellulose formed with a concentric annular stiffening corrugationand fiat portions on the inside and the outside of the same,substantially as described.

14. In sound recording apparatus, the combination with a recordingstylus and a resilient member carrying the same, of a diaphragm, andconnecting means having a universal connection with said resilientmemher and also with said diaphragm, substantially-as described. a

This specification signed and witnessed this 7th day of June 1910.

THOS. A. EDISON. Witnesses:

DYER SMITH, J. M. CANFIELD.

It is hereby certified that in Letters Patent No. 1,126,428, grantedJanuary '26, 1915, noon the application of Thomas A. Edison, of LlewllynPark, West Orange, New Jersey, for an improvement in Sound-RecordingApparatus, an error appears in the printed'specification requiringcorrection as follows: Page 1, line 64,

second occurrence, for the word of read or; and that the said LettersPatent should be read with this correction therein that the same mayconform to the record of the casein the Patent Ofiice. "I

Signed and sealed this 9th day of March, A. D., 1915.

[SEAL] J. T. NEWTON,

Acting Commissioner 0 Patents.

